Social bonds are fundamental in human society. Parent-child and spousal bonds are universal human behaviors and form the underpinnings of the family unit. Deficits in such bonds may lead to societal ills such as child abuse, divorce, and drug and alcohol abuse, while strong social attachments may actually be "protective" against substance abuse. Further, the inability to form or maintain meaningful social bonds is often diagnostic of psychological disorders such as autism. Thus, understanding how social bonds are formed may provide clues about the underlying causes of such disorders. We have begun to examine the neural basis of social attachment using pair-bonding in a monogamous rodent species, the prairie vole, as a model system. These animals form strong social bonds that can be readily quantified in an experimental setting and that provide a benchmark by which the effects of experimental manipulations can be assessed. Recent studies using voles have implicated the mesolimbic dopamine system in pair-bonding. Dopamine released within the brain is thought to be involved in reward processing that may play a role in pair-bonding, and such release has been found to be critical in the formation and maintenance of pair-bonds. Although earlier studies established a role for dopamine in pair-bonding, they examined only the target of released dopamine while the source of the dopamine remains unexplored. The ventral tegmental area (VTA) is an important source of dopamine and experimental manipulations of the VTA can significantly alter dopamine release. Together, these observations suggest a role for the VTA in pair-bonding. These studies will combine neuroanatomical, pharmacological, and behavioral methods to evaluate the overall hypothesis that the VTA is a critical part of the brain circuitry that underlies pair-bond formation and maintenance. The results of these studies will further our understanding of the brain circuitry involved in social attachment, and thus provide insights into the causes of a variety of human ailments. [unreadable] [unreadable]